The present invention relates generally to a clip fitting for a hose. More specifically, the invention is directed to a clip fitting having, among other things, at least one hose clip mounted on a hose nipple that includes at least one O-ring seal wherein the hose clip positions at least one clamp over the O-ring seal.
Many polyamide lined air-conditioning (A/C) system hoses are inflexible due to the thickness of the polyamide layer. This can cause hose routing difficulties, especially for field assembled lines when installing retrofit mobile A/C units.
The present invention provides an improved clip fitting for a relatively flexible polyamide veneer A/C hose. It has been found that the present invention provides excellent sealing performance between the fitting and the flexible hose over wide temperature and pressure ranges as compared to prior art fittings.
An example of a prior art fitting is shown in International Publication No. WO 95/33157 (Manuli). The Manuli reference discloses a hose fitting for A/C applications. The fitting includes a hose nipple that contains two rectangular circumferential grooves that accept gaskets. The purpose of the gaskets is to form a seal between a polyamide inner hose lining and the nipple O.D. When a force is applied perpendicular to and towards the axis of the hose, on the gaskets' arced surfaces, the gaskets deform in both directions parallel to the axis of the hose. This is permitted by the width of the grooves which are significantly wider than the gaskets. Hose clamps located over the gaskets and the interference fit between the hose and nipple are responsible for the force which causes the deformation of the gaskets. The shape of the gaskets provides resistance to removal of the gaskets from the grooves during assembly of the hose to the nipple.
Nipple retention force is obtained through an interference fit of the nipple to the hose, thus increasing the friction between the hose I.D. and the nipple O.D. Further nipple retention force is provided by the concentric deformation of the hose cover by the hose clamps. By applying a force perpendicular to and towards the axis of the hose, the clamps increase the friction between the hose I.D. and nipple O.D. Also, the hose clamps are located behind each of two barbed serrations of the hose nipple. This forms a mechanical lock between the area of high compression created by the hose clamp and the barbed serrations. Further, the polyamide liner is sufficiently thick so that it is able to resist tearing due to the relatively high force of the barbed serrations on the liner. If the hose is allowed to radially expand as it is pressurized, the effectiveness of the mechanisms responsible for nipple retention force is reduced. The potential for this radial expansion is resisted by two heavy fabric reinforcing braids.
The present invention seals by the placement of two O-ring seals between the nipple O.D. and the hose I.D. These O-rings are held by grooves dimensioned so that deflection of the seals when under radial compression is virtually eliminated. As the hose ages and the rubber hose begins to flow away from the areas of high compression (the sealing areas), the O-ring seals maintain their original shapes and positions. Because only a small portion of the O-ring seals' surfaces are exposed to the hose I.D., a relatively higher sealing pressure is achieved when a force perpendicular to and towards the axis of the hose is applied to such surfaces. These features promote a longer sealing life. On the contrary, the fitting of the Manuli reference seals by the use of two gaskets located between the nipple O.D. and hose I.D. These gaskets are contained in grooves dimensioned so that the gaskets are permitted to deform when they are radially compressed. As the hose ages, both the hose's rubber layers and the gaskets flow away from the areas of high compression. Because each gasket exposes a larger surface area to the hose I.D., the sealing pressure obtained by applying a force perpendicular to and towards the axis of the hose is relatively small. These features lead to a relatively shorter seal life.
The fitting of the present invention maintains the position of the O-ring seals during the assembly of the hose to the nipple by the O-ring grooves' dimensions. Each side of an O-ring groove is dimensioned so that the O-ring cross-section's center point is located below the edge of the groove. On the contrary, the Manuli reference fitting utilizes gaskets that are shaped so that they resist rolling.
The present invention utilizes the friction between the hose O.D. and the I.D. of the hose clamps. This is achieved through the use of a hose cage which, in one embodiment, snaps into a groove on the nipple and retains the clamps in two channels. The hose cage mechanically locks the nipple to transfer the friction force from the O.D. of the hose to the nipple. The Manuli reference fitting achieves nipple retention through the utilization of a much thicker polyamide liner to resist tearing under the friction load of the nipple on the hose liner. It also uses two heavy reinforcement braids that allow the hose to resist radial expansion during pressurization. The use of these hose features for nipple retention results in a hose that is relatively inflexible.
Finally, the present invention utilizes hose cages which snap onto the nipple at fixed locations. The clip contains two channels which locate the hose clamps on the hose cover. The Manuli reference fitting utilizes a bar which is permanently connected to the two hose clamps and locates off of the end of the hose.
Accordingly, the present invention provides an improved fitting that overcomes the above-identified problems associated with prior art fittings.